Open enrollment for 2014 Medicare Advantage plans (which cover both medical and drug costs) and Part D prescription-drug plans runs from October 15 to December 7, and you can find out about all of the plans in your area by using the Medicare.gov Plan Finder tool. Even if your plan's premiums have remained about the same, it's important to look at the co-payments for medical care and your prescription drugs, the plan's maximum out-of-pocket costs, its provider and pharmacy networks, and any extra coverage.

Go to the Medicare.gov Plan Finder, type in your zip code and the type of plan you have now (Medicare Advantage plans are called "Medicare Health Plans" in the tool), enter your drugs and dosages, and select up to two nearby pharmacies.

You'll see how all of the Medicare Advantage plans in your area compare with your current plan. Look at the monthly premium (which doesn't include the charge for Medicare Part B ), but also focus on the "estimated annual health and drug costs" column, which adds up the anticipated out-of-pocket costs for premiums, co-payments and deductibles for people in good health. (To see the estimated costs for someone in poor or excellent health, click on "refine your plan results" and then "change health status.") Some Medicare HMO plans with no premiums beyond the Part B charge are boosting their co-payments significantly, says Ross Blair, of eHealthMedicare.com.

You can also compare up to three plans in more detail. Click on "Health Plan Benefits" for a breakdown of the co-payments and other out-of-pocket costs for inpatient hospital care, doctors' office visits, skilled nursing facility care, emergency care, specialist office visits and other types of care. Pay special attention to coverage for types of care you frequently receive.

Because you never know exactly what kind of medical care you'll need during the year -- or if you'll develop a medical condition -- it's also important to look at the plans' out-of-pocket spending limit, which is the most you'd have to pay for covered expenses for the year. Maximum out-of-pocket costs can range from about $2,500 to $6,700, depending on the plan. Also see if a plan offers dental, vision and hearing coverage.

Click on the tab for the plans' star ratings, which assess coverage, the effectiveness of communications, and customer service. (You can switch into a plan with a five-star rating anytime during the year, even after open-enrollment season, although many areas do not have five-star plans.)

One important step: See if your doctors, hospitals, pharmacies and other providers are in-network. You can find a link to the plan's Web site (where you can search for network providers) in the "Plan Overview" section, or you can contact the plan directly to confirm that your doctors will remain in the plan next year.

Pay attention to a name change that could affect how the plan covers out-of-network doctors. Diane Omdahl, of 65 Incorporated, a Medicare education site, says some plans are changing from an HMO with a point-of-service option (which charges a higher co-payment to see out-of-network doctors) to a straight HMO in 2014, which means it covers services only in the network. "They must either find a specialist in-network or pay for those services out of pocket, with no coverage," she says. You can also find information about any changes in your current plan in the Annual Notice of Change form, which you should have received from your insurer in late September.

To see lists of the best Medicare Advantage plans by area based on estimates of typical total costs for people in good, fair and poor health, check out HealthMetrix Research's Cost Share Report at MedicareNewsWatch.com. You'll see a link there to the Senior Choice Gold Awards, which recognize Medicare Advantage plans with the best value.

You can get help comparing plans over the phone or in person from your State Health Insurance Assistance Program (go to ShipTalk.org or call 800-633-4227 for contact information).